In view of the disadvantages of the traditional fixed frames of scooters that are heavy and bulky and take a lot of space, an assembly type electric scooter frame that combines a front frame with and a rear frame has been developed in the industry to comply with regulation of different countries and meet consumers' diversified requirements.
Please referring to FIG. 1, a conventional electric scooter frame 1 includes a front frame 11 and a rear frame 12 that are both made by welding tubes with rectangular cross section together. It also has a plurality of front wheels 13 installed on the front frame 11, a plurality of rear wheels 14 installed on the rear frame 12, a battery set 15 and a transmission means 16 to drive the rear wheels 14. The rear frame 12 has a support tube 17 extending upward to hold a seat 18. The front frame 11 is coupled with an operation handlebar 19 extending upwards at the front side to turn the front wheels 13. The front frame 11 and the rear frame 12 further are covered by a housing. Due to difference of physical size and built between eastern and western people, the specifications and regulations of the scooter also are different in different countries, such as length limitation. Hence producers have to make the scooters at different lengths to meet the requirements of different countries.
Applicant also provides an improved assembling frame (disclosed in Taiwan utility patent No. M276772 entitled “Walking assisted scooter frame structure”) as shown in FIG. 2. It includes mainly a scooter frame 2 coupled with a handler frame 23 a front end thereof. The scooter frame 2 includes a rear frame 22 at a rear end thereof to hold a drive mechanism and a front frame 21 at the front end. The front frame 21 includes two longitudinal support bars 211 extending respectively forward from two sides of the front end to form two fastening portions 212 with a plurality of apertures 213 formed on the fastening portions 212, and a coupling bar 214 extending forward from the middle of the front end. The handler frame 23 includes a transverse support bar 24 with two fastening plates 241 fastened at two ends thereof. The two fastening portions 212 of the front frame 21 are mounted onto the two fastening plates 241 through screw elements 231 to fasten the front frame 21 and the handler frame 23 together.
However, in practice the aforesaid electric scooter frame still has problems yet to be resolved, notably:
a. The frame requires dedicated fixtures for the welding process. The welding process is complicated and time-consuming. Hence production efficiency is lower.
b. It needs a greater number of components and its total weight is higher. Also, the frame generally is made by welding of metal material. The welding joints of the frame often have inconsistent strength characteristics that could result in deficient reliability.
c. Greater dimension variances. Since the frame is assembled by welding, misalignment and welding deformation could easily take place that often result in errors. As a result, dimension variances of conventional electric scooter frame are greater. When the errors exceed an allowable range, the finished welding portions have to be dismantled and the welding has to be redone. This not only wastes a lot of working time, production efficiency also suffers.
From the perspective of the producers, by fabricating a common bar frame for electric scooters and preparing other smaller accessories such as transverse bars, they can be mated for assembly to provide a wide variety of products. Not only product transportation is easier, transportation cost also is lower. It also can greatly reduce inventory and save storage space, thus provide even more benefits.